PHYLOGENY AND THE TREE OF LIFE
CONCEPT 1: PHYLOGENIES SHOW EVOLUTIONARY RELATIONSHIP
Phylogeny: Evolutionary history of a species or a group of species
Systematics: A discipline focused on classifying organisms and determining their evolutionary relationships
Taxon: Taxonomic unit at any level of the hierarchy
Phylogenetic Tree: Branching diagram used to represent evolutionary history of organisms
Branch Point/Node: Divergence of two species
Sister Taxa: Group of organisms that share an immediate common ancestor
Rooted Tree: Includes branch to represent the last common ancestor of all the taxa in the tree
Basal Taxon: Diverges early in the history of a group and originates near the last common ancestor of the
whole group
Polytomy: branch from which more that two groups emerge
What we can and cannot learn from phylogenetic trees
1. Phylogenetic trees show patterns of descent not phenotypic similarity
2. Phylogenetic trees do not indicate when species evolved or how much change occurred in a lineage
3. It should not be assumed that a taxon evolved from the taxon next to it.